Centrifugal Pump Impeller Levitation via Balanced Magnetic Forces
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Solution Overview
Problem
Centrifugal pumps face challenges in maintaining sufficient rigidity to prevent impeller contact with the housing due to limited magnetic coupling force and unbalanced attractive forces, leading to potential contact during radial movement and disturbance.
Innovation Solution
A centrifugal pump design with balanced attractive forces between magnetic elements and hydrodynamic bearing grooves, ensuring equal changes in force with radial eccentricity, and enhanced radial rigidity through multiple magnets and coils, maintains a consistent levitation gap and resistance to disturbances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If magnetic coupling force is increased to improve radial rigidity, then impeller stability improves, but device complexity increases due to additional magnets and coils
Solution Approach 1:
The magnetic coupling system is segmented into multiple independent magnet-coil pairs arranged circumferentially around the impeller. Each pair acts as an independent actuator, allowing distributed control of radial position and enabling stable levitation through coordinated activation of multiple segments rather than requiring a single complex magnetic system
Solution Approach 2:
The patent combines magnetic coupling forces with hydrodynamic bearing effects to achieve stable impeller support. The magnetic system provides active radial positioning while the hydrodynamic grooves provide passive axial support and damping, merging two different physical mechanisms to solve the rigidity problem without requiring purely magnetic solutions
2Reliability
If attractive forces are increased to maintain levitation gap, then impeller-housing contact is prevented, but manufacturing precision requirements increase due to unbalanced forces
Solution Approach 1:
The patent employs asymmetric positioning of magnetic elements and coils to counterbalance attractive forces. By strategically placing magnets and coils at specific angular positions and with different strengths, the system creates intentional asymmetric force distributions that cancel out unbalanced attractive forces, maintaining levitation gap consistency without requiring ultra-precise manufacturing tolerances
Solution Approach 2:
The system incorporates sensors to detect impeller position and magnetic field strength, providing feedback to a control system that adjusts coil currents in real-time. This active feedback control compensates for manufacturing variations and maintains consistent levitation gap despite imperfections in magnetic element positioning or strength
3Stability of the object's composition
If multiple magnetic elements are added to enhance radial rigidity, then resistance to disturbance improves, but use of energy increases due to additional electromagnetic actuators
Solution Approach 1:
The magnetic actuators operate in periodic cycles, activating only when disturbance is detected or predicted. The system uses sensors to monitor impeller position and activates specific magnet-coil pairs only when correction is needed, rather than maintaining continuous high-energy fields from all actuators, thereby reducing average energy consumption while maintaining disturbance resistance
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design improves resistance to disturbances and prevents impeller contact with the housing, maintaining efficient operation and reducing the risk of hemolysis and thrombus formation by ensuring balanced attractive forces and consistent levitation.
Implementation Method 1
first attractive force between the first and second magnetic elements and second attractive force between the third magnetic element and the drive means are balanced with each other
Implementation Method 2
a first groove for hydrodynamic bearing is formed in the one surface of the impeller or in the inner wall of the first chamber facing the one surface, and a second groove for hydrodynamic bearing is formed in the other surface of the impeller or in the diaphragm facing the other surface
Implementation Method 3
an impeller for delivering liquid by centrifugal force during rotation
Data Source
AI summary
In this centrifugal blood pump apparatus, one permanent magnet is provided in one surface of an impeller, a second permanent magnet is provided in an inner wall of a blood chamber, a third permanent magnet is provided in the other surface of the impeller, and a fourth permanent magnet and a rotor for driving the impeller to rotate are provided, with an diaphragm being interposed. An amount of change in attractive force between the first permanent magnet and the second permanent magnet and an amount of change in attractive force between the third and fourth permanent magnets when the impeller is eccentric are made substantially equal to each other. Therefore, a levitation position of the impeller can always be maintained at a substantially central position in a housing.